Impaired circadian variation of platelet activity in patients with sleep apnea.

BACKGROUND: Cardiovascular diseases are frequent in patients with obstructive sleep apnea (OSAS). There is evidence that the day-night pattern of myocardial infarction and sudden cardiac death observed in the general population is altered in patients with OSAS. This study investigates potential abnormalities in the circadian profiles of platelet activity in OSAS. METHODS: We studied 37 patients with OSAS [7 of whom were also studied after 3 months on continuous positive airway pressure (CPAP) treatment] and 11 controls. In each subject, we obtained six different blood samples during 24-h period (2200, 0200, 0600, 1000, 1400, and 1800 hours). Platelet activity was determined by flow cytometry immediately after sampling. RESULTS: We found that nocturnal platelet activity was significantly increased in patients with OSAS (p = 0.043) and that effective treatment with CPAP decreased platelet activity in these patients but differences just failed to reach statistical significance (p = 0.063). CONCLUSIONS: OSAS is associated with increased platelet activity during the night, and that this appears to be improved by chronic use of CPAP. These results may contribute to explain the high prevalence of cardiovascular events during sleep in OSAS.

Non-synonymous polymorphism in the neuropeptide S precursor gene and sleep apnea.

BACKGROUND: Obstructive sleep apnea syndrome (OSAS) is a complex disease with a strong genetic basis. One of the primary molecular domains affected by OSAS is sympathetic activity. Neuropeptide S (NPS) plays an important role in the regulation of the sleep-wakefulness cycle, anxiety states, and daytime sleepiness. It is important to study neuropeptides related to sympathetic activity regulation and how their function could be modified by genetic variants affecting the expression of these molecules. OBJECTIVES: We investigated the association of the non-synonymous polymorphism rs4751440 in the NPS precursor gene with OSAS and certain variables related to OSAS (daytime sleepiness, body mass index (BMI), insulin resistance, and blood pressure). This polymorphism causes an amino acid substitution in exon 3 of the human NPS precursor gene. PATIENTS AND METHODS: We included 253 OSAS patients and 70 healthy subjects. Genotyping was done by polymerase chain reaction using specific flanking primers and agarose gel electrophoresis. Daytime sleepiness, BMI, plasma levels of high-density lipoprotein, glucose, total cholesterol, insulin, triglycerides, and the homeostasis model assessment index were also determined. RESULTS: A similar genotypic and allelic distribution was found in OSAS patients and controls. The risk of OSAS was not associated with the rs4751440 polymorphism. There was no significant interaction between daytime sleepiness or metabolic variables and the rs4751440 polymorphism. CONCLUSION: Genotypic and allelic frequency distribution of the rs4751440 polymorphism was similar in OSAS patients and controls. In this population-based study, we could not show a significant association between rs4751440 polymorphism and susceptibility to OSAS or certain phenotypes related to OSAS (daytime sleepiness, BMI, systolic blood pressure, and insulin resistance) with the exception of diastolic blood pressure.

Nontypeable Haemophilus influenzae clearance by alveolar macrophages is impaired by exposure to cigarette smoke.

Nontypeable Haemophilus influenzae (NTHI) is an opportunistic gram-negative pathogen that causes respiratory infections and is associated with progression of respiratory diseases. Cigarette smoke is a main risk factor for development of respiratory infections and chronic respiratory diseases. Glucocorticoids, which are anti-inflammatory drugs, are still the most common therapy for these diseases. Alveolar macrophages are professional phagocytes that reside in the lung and are responsible for clearing infections by the action of their phagolysosomal machinery and promotion of local inflammation. In this study, we dissected the interaction between NTHI and alveolar macrophages and the effect of cigarette smoke on this interaction. We showed that alveolar macrophages clear NTHI infections by adhesion, phagocytosis, and phagolysosomal processing of the pathogen. Bacterial uptake requires host actin polymerization, the integrity of plasma membrane lipid rafts, and activation of the phosphatidylinositol 3-kinase (PI3K) signaling cascade. Parallel to bacterial clearance, macrophages secrete tumor necrosis factor alpha (TNF-alpha) upon NTHI infection. In contrast, exposure to cigarette smoke extract (CSE) impaired alveolar macrophage phagocytosis, although NTHI-induced TNF-alpha secretion was not abrogated. Mechanistically, our data showed that CSE reduced PI3K signaling activation triggered by NTHI. Treatment of CSE-exposed cells with the glucocorticoid dexamethasone reduced the amount of TNF-alpha secreted upon NTHI infection but did not compensate for CSE-dependent phagocytic impairment. The deleterious effect of cigarette smoke was observed in macrophage cell lines and in human alveolar macrophages obtained from smokers and from patients with chronic obstructive pulmonary disease.

A controlled trial of noninvasive ventilation for chronic obstructive pulmonary disease exacerbations.

PURPOSE: This prospective, multicenter, double-blind, placebo-controlled study tested the hypothesis that noninvasive positive pressure ventilation reduces the need for endotracheal intubation in patients hospitalized in a pulmonary ward because of acute exacerbation of chronic obstructive pulmonary disease. MATERIALS AND METHODS: Seventy-five consecutive patients with exacerbation (pH, 7.31 +/- 0.02; Pao(2), 45 +/- 9 mm Hg; Paco(2), 69 +/- 13 mm Hg) were randomly assigned to receive noninvasive ventilation or sham noninvasive ventilation during the first 3 days of hospitalization on top of standard medical treatment. RESULTS: The need for intubation (according to predefined criteria) was lower in the noninvasive ventilation group (13.5% vs 34%, P < .01); in 31 patients with pH not exceeding 7.30, these percentages were 22% and 77%, respectively (P < .001). Arterial pH and Paco(2) improved in both groups, but changes were enhanced by noninvasive ventilation. Length of stay was lower in the noninvasive ventilation group (10 +/- 5 vs 12 +/- 6 days, P = .06). In-hospital mortality was similar in both groups. CONCLUSIONS: These results demonstrate that noninvasive positive pressure ventilation, in a pulmonary ward, reduces the need for endotracheal intubation, particularly in the more severe patients, and leads to a faster recovery in patients with acute exacerbation of chronic obstructive pulmonary disease.

Prediction of risk of COPD exacerbations by the BODE index.

OBJECTIVES: This study assesses the power of the BODE index, a multidimensional grading system that predicts mortality, to predict subsequent exacerbations in patients with COPD. DESIGN: Prospective cohort study. PATIENTS AND INTERVENTIONS: A total of 275 COPD patients were followed every 6 months up to 8 years (median of 5.1 years). Baseline clinical variables were recorded and the BODE index was calculated. We investigated the prognostic value of BODE quartiles (scores 0-2, 3-4, 5-6 and 7-10) for both the number and severity of exacerbations requiring ambulatory treatment, emergency room visit, or hospitalization. RESULTS: The annual rate of COPD exacerbations was 1.95 (95% CI, 0.90-2.1). The mean time to a first exacerbation was inversely proportional to the worsening of the BODE quartiles (7.9 yrs, 5.7 yrs, 3.4 yrs and 1.3 yrs for BODE scores of 0-2, 3-4, 5-6 and 7-10, respectively). Similarly, the mean time to a first COPD emergency room visit was 6.7 yrs, 3.6 yrs, 2.0 yrs and 0.8 yrs for BODE quartiles (all p<0.05). Using ROC curves, the BODE index was a better predictor of exacerbation than the FEV(1) alone (p<0.01). CONCLUSIONS: The BODE index is a better predictor of the number and severity of exacerbations in COPD than FEV(1) alone.

Increased plasma levels of asymmetric dimethylarginine and soluble CD40 ligand in patients with sleep apnea.

BACKGROUND: Cardiovascular (CV) diseases are a leading cause of mortality and they are frequent in patients with the obstructive sleep apnea syndrome (OSAS). OBJECTIVES: In this study we investigated if OSAS influences CV function independently of other CV risk factors frequently present in these patients (e.g. obesity, high blood pressure). METHODS: We compared plasma markers of endothelial dysfunction, asymmetric dimethylarginine (ADMA) and endothelin-1 (ET-1), and atherosclerosis progression (soluble fraction of the CD40 ligand, sCD40L) in OSAS patients with (n = 23) and without (n = 18) concurrent CV risk factors, as well as in healthy subjects (n = 23). RESULTS: Plasma ADMA (p < 0.01) and sCD40L (p < 0.05) were abnormally increased in patients with OSAS versus healthy controls, but they were not influenced by the presence or absence of CV risk factors in OSAS. ET-1 levels were not different between the three groups of subjects studied. CONCLUSIONS: OSAS is associated with endothelial injury and atherosclerosis progression independently of other CV risk factors.

Airway wall thickening and emphysema show independent familial aggregation in chronic obstructive pulmonary disease.

RATIONALE: It is unclear whether airway wall thickening and emphysema make independent contributions to airflow limitation in chronic obstructive pulmonary disease (COPD) and whether these phenotypes cluster within families. OBJECTIVES: To determine whether airway wall thickening and emphysema (1) make independent contributions to the severity of COPD and (2) show independent aggregation in families of individuals with COPD. METHODS: Index cases with COPD and their smoking siblings underwent spirometry and were offered high-resolution computed tomography scans of the thorax to assess the severity of airway wall thickening and emphysema. MEASUREMENTS AND MAIN RESULTS: A total of 3,096 individuals were recruited to the study, of whom 1,159 (519 probands and 640 siblings) had technically adequate high-resolution computed tomography scans without significant non-COPD-related thoracic disease. Airway wall thickness correlated with pack-years smoked (P < or = 0.001) and symptoms of chronic bronchitis (P < 0.001). FEV(1) (expressed as % predicted) was independently associated with airway wall thickness at a lumen perimeter of 10 mm (P = 0.0001) and 20 mm (P = 0.0013) and emphysema at -950 Hounsfield units (P < 0.0001). There was independent familial aggregation of both the emphysema (adjusted odds ratio, 2.1; 95% confidence interval, 1.1-4.0; P < or = 0.02) and airway disease phenotypes (P < 0.0001) of COPD. CONCLUSIONS: Airway wall thickening and emphysema make independent contributions to airflow obstruction in COPD. These phenotypes show independent aggregation within families of individuals with COPD, suggesting that different genetic factors influence these disease processes.

Systemic inflammation after inspiratory loading in chronic obstructive pulmonary disease.

OBJECTIVE: Patients with chronic obstructive pulmonary disease (COPD) present systemic inflammation. Strenuous resistive breathing induces systemic inflammation in healthy subjects. We hypothesized that the increased respiratory load that characterizes COPD can contribute to systemic inflammation in these patients. PATIENTS AND METHODS: To test this hypothesis, we compared leukocyte numbers and levels of circulating cytokines (tumor necrosis factor alpha [TNFalpha], interleukin-1beta [IL-1beta], IL-6, IL-8, and IL-10), before and 1 hour after maximal incremental inspiratory loading in 13 patients with stable COPD (forced expiratory volume in one second [FEV1] 29 +/- 2.5% ref) and in 8 healthy sedentary subjects (FEV1 98 +/- 5% ref). RESULTS: We found that: (1) at baseline, patients with COPD showed higher leukocyte counts and IL-8 levels than controls (p < 0.01); and, (2) one hour after maximal inspiratory loading these values were unchanged, except for IL-10, which increased in controls (p < 0.05) but not in patients with COPD. CONCLUSIONS: This study confirms the presence of systemic inflammation in COPD, shows that maximal inspiratory loading does not increase the levels of pro-inflammatory cytokines (IL-1beta, IL-8) in COPD patients or controls, but suggests that the former may be unable to mount an appropriate systemic anti-inflammatory response to exercise.

Endothelial function and circulating endothelial progenitor cells in patients with sleep apnea syndrome.

BACKGROUND: Endothelial dysfunction and cardiovascular diseases are frequent in patients with obstructive sleep apnea (OSA). Circulating endothelial progenitor cells (EPCs) contribute to repair dysfunctional endothelium and have been related to increased cardiovascular risk. OBJECTIVES: We tested the hypothesis that the number of circulating EPCs may be altered in OSA patients. METHODS: EPCs (CD34+ VEGF-R2+) were isolated and quantified from peripheral blood samples of OSA patients (n = 13) and healthy controls (n = 13) matched for age and sex. All subjects were free of any other known cardiovascular risk factors. The plasma levels of vascular endothelial growth factor (VEGF) were also determined, and the endothelium-dependent and endothelium-independent vascular function was assessed in all subjects. RESULTS: Patients with OSA had lower levels of EPCs (p < 0.05) and higher plasma levels of VEGF (p < 0.05) than controls. Endothelial function was not different between OSA and controls. CONCLUSIONS: Patients with OSA free of any other known cardiovascular risk factor show a reduced number of circulating EPCs and an increase in plasma VEGF levels. These alterations may contribute to future endothelial dysfunction in these patients.

Pulmonary and systemic hepatocyte and keratinocyte growth factors in patients with chronic obstructive pulmonary disease.

BACKGROUND: The potential role of growth factors in chronic obstructive pulmonary disease (COPD) has begun to be addressed only recently and is still poorly understood. For this study, we investigated potential abnormalities of hepatocyte growth factor (HGF) and keratinocyte growth factor (KGF) in patients with COPD. METHODS: To this end, we compared the levels of HGF and KGF, measured by enzyme-linked immunosorbent assay (ELISA), in bronchoalveolar lavage (BAL) fluid and in serum in 18 patients with COPD (62 +/- 9 yrs, forced expiratory volume in one second [FEV1] 57 +/- 12% ref, X +/- standard deviation of mean), 18 smokers with normal lung function (58 +/- 8 yrs, FEV1 90 +/- 6% ref) and 8 never smokers (67 +/- 9 yrs, 94 +/- 14% ref). RESULTS: We found that in BAL, HGF levels were higher in patients with COPD than in the other two groups whereas, in serum, HGF concentration was highest in smokers with normal lung function (p < 0.01). KGF levels were not significantly different between groups, neither in blood nor in BAL (most values were below the detection limit). CONCLUSIONS: These results highlight a different response of HGF in BAL and serum in smokers with and without COPD that may be relevant for tissue repair in COPD.

Effect of continuous positive airway pressure on the risk of road accidents in sleep apnea patients.

BACKGROUND: Continuous positive airway pressure (CPAP) reduces daytime somnolence in the obstructive sleep apnea syndrome (OSAS) and may contribute to a reduction in the risk of motor vehicle accidents. OBJECTIVE: To evaluate the effects of CPAP on automobile collisions in patients with OSAS. METHODS: We compared the number of motor vehicle accidents in 80 patients with OSAS and 80 healthy subjects during the 2 years before and the 2 years after study entry, at which CPAP treatment was initiated. RESULTS: Patients with OSAS had a 2.6 times higher risk of suffering an automobile collision compared to controls (rate ratio, RR=2.57; 95% confidence interval, CI=1.30-5.05). After 2 years of CPAP treatment, the rate of collisions was reduced more than half in patients with OSAS (RR=0.41; 95% CI=0.21-0.79), but this occurred also in controls (RR=0.49; 95% CI=0.17-1.40). The magnitude of this fall between groups was not different (p for interaction=0.68), even after adjusting for body mass index, alcohol intake and Epworth scale. CONCLUSIONS: Patients with OSAS have an increased risk of suffering a traffic collision. This risk was significantly reduced after their inclusion in the study. Yet, as this reduction also occurred in the control group, this effect may not be due to CPAP therapy.

Angiotensin-converting-enzyme gene polymorphisms, smoking and chronic obstructive pulmonary disease.

While tobacco smoking is the main risk factor for chronic obstructive pulmonary disease (COPD) only a fraction of smokers go on to develop the disease. We investigated the relationship between the insertion (I)--deletion (D) polymorphisms in the Angiotensin converting enzyme (ACE) gene and the risk of developing COPD in smokers by determining the distribution of the ACE genotypes (DD, ID and II) in 151 life-long male smokers. 74 of the smokers had developed COPD (62 +/- 2 years; FEV1 44 +/- 6% reference) whereas the rest retained normal lung function (56 +/- 2 yrs; FEV1 95 +/- 3% reference). In addition, we genotyped 159 males recruited randomly from the general population. The prevalence of the DD genotype was highest (p = 0.01) in the smokers that developed COPD and its presence was associated with a 2-fold increase in the risk for COPD (OR 2.2; IC95% 1.1 to 5.5). Surprisingly, the 151 individuals in the smoking population did not demonstrate Hardy-Weinberg equilibrium unlike the 159 recruited from the general population. Our results suggest that ACE polymorphisms are associated with both the smoking history of an individual and their risk of developing COPD.

Expression of Toll-like receptor 2 is up-regulated in monocytes from patients with chronic obstructive pulmonary disease.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is characterised by pulmonary and systemic inflammation which flare-up during episodes of acute exacerbation (AECOPD). Given the role of Toll-like receptors (TLRs) in the induction of inflammatory responses we investigated the involvement of TLRs in COPD pathogenesis. METHODS: The expression of TLR-2, TLR-4 and CD14 in monocytes was analyzed by flow cytometry. To study the functional responses of these receptors, monocytes were stimulated with peptidoglycan or lipopolysaccharide and the amounts of TNFalpha and IL-6 secreted were determined by ELISA. RESULTS: We found that the expression of TLR-2 was up-regulated in peripheral blood monocytes from COPD patients, either clinically stable or during AECOPD, as compared to never smokers or smokers with normal lung function. Upon stimulation with TLR-2 ligand monocytes from COPD patients secreted increased amounts of cytokines than similarly stimulated monocytes from never smokers and smokers. In contrast, the expressions of TLR-4 and CD14 were not significantly different between groups, and the response to lipopolysaccharide (a TLR-4 ligand) stimulation was not significantly different either. At discharge from hospital TLR-2 expression was down-regulated in peripheral blood monocytes from AECOPD patients. This could be due to the treatment with systemic steroids because, in vitro, steroids down-regulated TLR-2 expression in a dose-dependent manner. Finally, we demonstrated that IL-6, whose plasma levels are elevated in patients, up-regulated in vitro TLR-2 expression in monocytes from never smokers. CONCLUSION: Our results reveal abnormalities in TLRs expression in COPD patients and highlight its potential relationship with systemic inflammation in these patients.

Systemic effects of chronic obstructive pulmonary disease.

Chronic obstructive pulmonary disease (COPD) affects various structural and functional domains in the lungs. It also has significant extrapulmonary effects, the so-called systemic effects of COPD. Weight loss, nutritional abnormalities, and skeletal muscle dysfunction are well-recognized systemic effects of COPD. Other less well-known but potentially important systemic effects include an increased risk of cardiovascular disease and several neurologic and skeletal defects. The mechanisms underlying these systemic effects are unclear, but they are probably interrelated and multifactorial, including inactivity, systemic inflammation, tissue hypoxia and oxidative stress among others. These systemic effects add to the respiratory morbidity produced by the underlying pulmonary disease and should be considered in the clinical assessment as well as the treatment of affected patients.

Long-term cardiovascular outcomes in men with obstructive sleep apnoea-hypopnoea with or without treatment with continuous positive airway pressure: an observational study.

BACKGROUND: The effect of obstructive sleep apnoea-hypopnoea as a cardiovascular risk factor and the potential protective effect of its treatment with continuous positive airway pressure (CPAP) is unclear. We did an observational study to compare incidence of fatal and non-fatal cardiovascular events in simple snorers, patients with untreated obstructive sleep apnoea-hypopnoea, patients treated with CPAP, and healthy men recruited from the general population. METHODS: We recruited men with obstructive sleep apnoea-hypopnoea or simple snorers from a sleep clinic, and a population-based sample of healthy men, matched for age and body-mass index with the patients with untreated severe obstructive sleep apnoea-hypopnoea. The presence and severity of the disorder was determined with full polysomnography, and the apnoea-hypopnoea index (AHI) was calculated as the average number of apnoeas and hypopnoeas per hour of sleep. Participants were followed-up at least once per year for a mean of 10.1 years (SD 1.6) and CPAP compliance was checked with the built-in meter. Endpoints were fatal cardiovascular events (death from myocardial infarction or stroke) and non-fatal cardiovascular events (non-fatal myocardial infarction, non-fatal stroke, coronary artery bypass surgery, and percutaneous transluminal coronary angiography). FINDINGS: 264 healthy men, 377 simple snorers, 403 with untreated mild-moderate obstructive sleep apnoea-hypopnoea, 235 with untreated severe disease, and 372 with the disease and treated with CPAP were included in the analysis. Patients with untreated severe disease had a higher incidence of fatal cardiovascular events (1.06 per 100 person-years) and non-fatal cardiovascular events (2.13 per 100 person-years) than did untreated patients with mild-moderate disease (0.55, p=0.02 and 0.89, p<0.0001), simple snorers (0.34, p=0.0006 and 0.58, p<0.0001), patients treated with CPAP (0.35, p=0.0008 and 0.64, p<0.0001), and healthy participants (0.3, p=0.0012 and 0.45, p<0.0001). Multivariate analysis, adjusted for potential confounders, showed that untreated severe obstructive sleep apnoea-hypopnoea significantly increased the risk of fatal (odds ratio 2.87, 95%CI 1.17-7.51) and non-fatal (3.17, 1.12-7.51) cardiovascular events compared with healthy participants. INTERPRETATION: In men, severe obstructive sleep apnoea-hypopnoea significantly increases the risk of fatal and non-fatal cardiovascular events. CPAP treatment reduces this risk.

Neuropeptide Y and leptin in patients with obstructive sleep apnea syndrome: role of obesity.

Neuropeptide Y (NPY) and leptin are two peptides involved in the regulation of body weight, energy balance, and sympathetic tone. This study investigates the independent role of apneas and obesity on NPY and leptin plasma levels in patients with obstructive sleep apnea syndrome (OSAS). To this end we compared their values in 23 obese (body mass index > 30 kg/m2) and 24 nonobese (body mass index < 27 kg/m2) patients with OSAS, and in 19 obese and 18 nonobese control subjects without OSAS. Patients who used continuous positive airway pressure for more than 4 hours/night were reexamined 3 and 12 months later. We found that NPY levels were increased (p < 0.01) in patients with OSAS independently of obesity. Leptin levels were also increased in OSAS but this was mostly associated to obesity. Continuous positive airway pressure treatment reduced NPY levels in all patients and leptin levels only in nonobese patients (p < 0.01). We concluded that NPY and leptin plasma levels are increased in patients with OSAS. Yet, whereas the former appear independent of obesity, the latter are mostly associated with obesity.

Expression of adhesion molecules during apoptosis of circulating neutrophils in COPD.

STUDY OBJECTIVES: Neutrophil accumulation occurs in the lungs of patients with COPD. This can be due to increased recruitment and/or delayed tissue clearance. Previous studies have described alterations in circulating neutrophils in these patients that can facilitate the former. Dysregulation of neutrophil apoptosis may contribute to the latter. This study investigated the potential abnormalities of the apoptotic process in COPD patients. DESIGN: Prospective study. SETTINGS: Outpatient clinic in a urban, tertiary hospital. PATIENTS: Fourteen stable patients with COPD, 8 smokers with normal lung function, and 8 healthy nonsmoking subjects. MEASUREMENTS AND RESULTS: We cultured circulating neutrophils that had been harvested from the study subjects at 2, 6, and 24 h. Apoptosis was assessed using flow cytometry by annexin binding and CD16 expression. The surface expression of the adhesion molecules Mac-1 (CD11b) and L-selectin (CD62L) also was determined by flow cytometry. The percentage of apoptotic neutrophils increased with time similarly in all groups. However, the surface expression of Mac-1 (CD11b) was higher, and that of L-selectin (CD62L) was lower, during apoptosis in the neutrophils of patients with COPD. CONCLUSIONS: These results show that, quantitatively, in vitro neutrophil apoptosis in COPD patients occurred at a rate similar to that found in healthy individuals and smokers with normal lung function. Qualitatively, however, the increased surface expression of Mac-1 (CD11b) and the decreased surface expression of L-selectin (CD62L) observed in the apoptotic neutrophils of COPD patients indicate increased activation during the apoptotic process. This may be relevant for the pathogenesis of COPD.

Skeletal muscle changes in patients with obstructive sleep apnoea syndrome.

Previous studies have shown that chronic hypoxia leads to changes in skeletal muscle structure (fibre size and type) and activities of several bioenergetic enzymes. Whether this occurs also in conditions characterised by intermittent hypoxia, such as the obstructive sleep apnoea syndrome (OSAS), is unknown. To explore this possibility, we obtained a needle biopsy of the quadriceps femoris in 12 consecutive stable outpatients with severe OSAS (52 +/- 9 year, apnoea-hypopnoea index 70 +/- 14 h(-1)) (x +/- SD) and in six healthy volunteers (49 +/- 8 year), where we quantified fibre type, size and protein content, as well as phosphofructo-kinase (PFK) and cytochrome oxidase (CytOx) activities. We found that fibre-type distribution was similar in patients and controls. In contrast, the diameter of type II fibres (74 +/- 10 microm vs. 56 +/- 11 microm, P < 0.05) and protein content (100 +/- 14 vs. 88 +/- 8 microg/mg) was higher in patients with OSAS. Likewise, we observed upregulation of CytOx (0.93 +/- 0.38 vs. 0.40 +/- 0.22 microkat/mg protein, P < 0.01) and PFK activities (5.35 +/- 4.8 vs. 1.3 +/- 1.3 microkat/ mg protein, P < 0.05) in patients with OSAS. These results show that, paralleling which occurs in conditions characterised by continuous hypoxia, patients with OSAS (and intermittent hypoxia) also show structural and bioenergetic changes in their skeletal muscle.

Long-term (72 hours) preservation of rat lungs.

OBJECTIVE: We sought to investigate whether the addition of ethanol to a preservation solution (as an antifreeze agent) might allow a reduction of the storage temperature to 0 degrees C without causing freezing damage and improve lung function after prolonged (72 hours) ischemia. METHODS: Lungs from Sprague-Dawley rats were ventilated and perfused ex vivo at 37 degrees C for 60 minutes in the following experimental groups: (1) the no ischemia and reperfusion (no I-R) group (n = 7), in which lungs were studied immediately after harvesting; (2) the LPD24 (n = 7) and (3) LPD72 (n = 8) groups, in which, after harvesting, lungs were flushed and immersed in low-potassium dextran solution and stored deflated at 10 degrees C for 24 and 72 hours, respectively, until reperfusion; and (4) the TEST72 group (n = 9), in which lungs were flushed and immersed in Krebs-Henseleit buffer with added ethanol (10 mL/L) after harvesting and stored deflated at 0 degrees C for 72 hours until reperfusion. RESULTS: Compared with the no I-R group, the other 3 groups had worse lung function, higher lung water content, and evidence of cell injury at reperfusion (P <.01). However, lung function at reperfusion (assessed on the basis of either effluent Po(2), peak airway pressure, or mean arterial pulmonary pressure) was better (P <.01) in the TEST72 group than in the LPD24 or LPD72 groups. Paradoxically, lung cell structure was better preserved in the LPD24 group than in the TEST72 group (or the LPD72 group). CONCLUSIONS: In this experimental model of rat lung ischemia-reperfusion injury, a low preservation temperature (0 degrees C) combined with the addition of ethanol to the preservation solution improves lung function at reperfusion after 72 hours of ischemia but fails to maintain lung cell structure.